Burglar alarm system for a movable closure



ay 22, 1956 A. G. KELLER BURGLAR ALARM SYSTEM FOR A MOVABLE CLOSURE 2Sheets-Sheet 1 Filed Aug. 2, 1952 I l 1- L INVENTOR. ALBERT G. KELLER WATTORNEY May 22, 1956 A. G. KELLER BURGLAR ALARM SYSTEM FOR A MOVABLECLOSURE 2 Sheets-Sheet 2 Filed Aug. 2, 1952 BURGLAR ALARM SYSTEM FOR AMOVABLE CLOSURE Albert G. Keller, Forest Hills, N. Y., assignor toHolmes Electric Protective Company, New York, N. Y., a corporation ofNew York Application August 2, 1952, Serial No. 302,390

7 Claims. (Cl. 340-276) My novel jack and plug may be arranged incombination with all types of movable closures, but they are especiallyWell suited for use with corrugated or sectional overhead doors. In thepast attempts to furnish a satisfactory burglar alarm device which couldbe readily installed on such a door and which would be responsive to aslight opening thereof have been unsuccessful.

It is an object of the present invention to provide a shorting jack andplug which form a portion of an electrical burglar alarm circuit andwhich can be arranged in combination with any movable closure so as toshort that portion of the circuit when it is attempted to open theclosure.

Another object of the invention is to provide a shorting jack and plugof the above mentioned type which are easily installed in combinationwith a movable closure, which can be easily disconnected from oneanother so as not to interfere with the authorized normal use of theclosure and which can be readily connected or set when the closure isclosed.

Still another object is to provide a shorting jack and plug thereforwhich are rugged, though small and light in weight, which areinstallable where they cannot be tempered with or rendered inoperativeby a person outside the building, and which nevertheless can be readilyseen from the inside to determine whether or not they are set.

The best mode in which it has been contemplated to apply the principlesof my improvements is shown in the accompanying drawings but these areto be deemed primarily illustrative because it is intended that thepatent shall cover by suitable expression in the appended claimswhatever features of patentable movelty exist in the inventiondisclosed.

In the accompanying drawings:

Fig. 1 shows in full lines a pair of shorting jacks and plugs installedin combination with a corrugated or seetional overhead door, the doorbeing closed and the plugs inserted in their respective jacks completingthe circuit. The dotted lines show the positions of the jacks and plugswhen the door is opened slightly, or when the plugs have been withdrawnfor authorized use of the door.

Fig. 2 is a medial cross sectional view of a shorting jack;

Fig. 2a is a side view of a portion of a plug, partly in medial crosssection;

Fig. 3 is another medial cross sectional view of a shorting jack showinga plug inserted therein, the plug also being shown in medial crosssection;

Fig. 4 is a cross sectional view of the jack taken as on line 44 of Fig.2;

Fig. 5 is a cross sectional view of the plug taken as on line 55 of Fig.2a;

Fig. 6 is a diagram showing the burglar alarm system of which theshorting jacks and plugs are parts and illustrating the circuitcondition when the plugs are inserted in the jacks;

Fig. 7 is a diagram similar to Fig. 6, but illustrating nited StatesPatent 0 2,747,177 Patented May 22, 1956 'ice the circuit condition whenthe plugs are separated from the jacks; i

Fig. 8 is another diagram similar to Fig. 6, but illustrating thecircuit condition when the cable across the closure has been cut orbroken; and

Fig. 9 is still another diagram which shows only that portion of thecircuit associated with the closure, illustrating what happens in thisportion when one of the plugs is pulled only partway out of its jack.

Referring now more particularly to Fig. 1 of the drawings, the closurebeing protected is a corrugated or sectional overhead door 10. Theportion of the burglar alarm circuit protecting this door comprises acable 12 leading from other parts of the circuit and entering one end ofa jack A flexibly secured to a frame 14 at the side of the door 10 by ashort length of chain 16 substantially as shown. When the door 10 isclosed this portion of the alarm system is put in readiness by insertinga plug B into the other end of the jack A. This plug is located on theend of another length of cable 18 extending across the door and securedthereto by a series of fasteners 20. At the other end of cable 18 is asecond plug B identical to plug B. This second plug is inserted in asecond jack A identical to jack A and secured to the frame 14 on theother side of the door with a chain 16' in the same manner as the firstmentioned jack. From this last mentioned jack a cable 12' leads to thenext attachment on the premises in the overall circuit. The jacks B andB are fastened to the door frames 14 and 14' respectively'in suchrelation to the cable 18 secured to the door that when the latter isentirely closed the jacks must be tipped upward and extended toward theplugs as far as the chains 16 and 16 will allow before the plugs can beinserted. Spring detents within the jacks which will presently bedescribed in more detail provide enough holding force to prevent theweight of the jacks from pulling away from the plugs.

When the door begins to open, as for instance when an unauthorizedperson attempts to enter the building, the cable 18 and plugs B and B onthe ends thereof move upward with the door, and since the jacks cannotbe so moved due to their chain connections with the fixed door frames,the plugs are pulled out of their jacks after the door has been opened aslight amount, the amount of opening required for this separationdepending on the slack between the points where the chains 16 and 16 arefastened to the door frames and the two cable fasteners 20 on the doorwhich are nearest the plugs. After being separated from the plugs bysuch an opening of the door, or when purposely disconnected to permitauthorized use of the door, the jacks hang down from their chains asshown by the dotted lines in Fig. 1.

Referring now to Fig. 2 each jack A (or A) comprises an outercylindrical casing 22 having at the end thereof a plug 24 provided witha suitable central hole 24a through which the cable 12 (or 12) entersthe jack. A portion of this plug 24 is reduced in diameter at 24b to fitwithin the cylindrical casing 22 and to provide a shoulder 240 againstwhich the end of the casing seats. One end of the short chain 16 (or 16)has secured thereto a ring 25 which passes through the head 26a of abolt 26 screwed into plug 24. A lock washer 28 prevents bolt 26 fromworking loose in the plug. At the other end of the cylindrical casing 22there is a somewhat similar plug 30 which is appropriately reduced indiameter at 30b to fit part way into the casing 22 and to provide ashoulder 3:00 to engage the end of the casing. These two end plugs areheld in place by a rod 32 located within the casing and having one endthreaded at 32a to screw into the plug 30. The other end of this rod 32has an enlarged portion 32b with an axial hole 32c tapped therein toreceive a bolt 34 passing through the plug 24. Tightening this boltholds the ends of the casing 22 firmly against the shoulders 24c and 300on the plugs 24 and 30, respectively. The central hole 30a in the endplug 30 is lined with a bushing 36 having an axial hole 36a, the outerend of which is flared to facilitate insertion and removal of the plug B(or B). The inner end 3617 of the bushing extends somewhat beyond theplug 30 and is reduced externally to receive an end plate 38a of a framemember 38. When the end plate has been slipped over this reduced end ofthe bushing the latter is peened over to secure this end plate to thebushing. A part of this end plate 38a "extends sideways from the bushingand has a hole through which the rod 32 extends. A shoulder 32d on therod clamps the end plate to the plug 30. Thus the frame 38 and thebushing are held firmly in place.

The frame 38 is disposed at the center of the casing 22 and servesto'support the various electrical conductors and their insulatingspacers. Adjacent the top side 3815 of the frame 38 is located arectangular strip of insulating material 40. Next to this insulationstrip 40 is a conductor strip 42, having a contact point 42a near theend thereof toward the plug 30. Adjacent to this conductor strip 42 isanother shorter rectangular insulation strip 44. Next to this insulationstrip 44 is another conductor strip 46, longer than the first mentionedconductor strip 42, having a small plate 46a welded thereon which canbear against the contact point 42a and having a ripple 46b at the endthereof which is located about opposite the side of the hole 36a in thebushing 36. Adjacent to this conductor strip 46 is still anotherinsulation strip 48 of the same size as insulation strip 44, and next tothis insulation strip 48 is another conductor strip 50 of the same sizeas conductor strip 42. The conductor strip 50 has disposed near its enda contact point 50a similar to contact point 42a on conductor strip 42.Another insulation strip 52 of the same size as insulation strips 44 and48 separates conductor strip 50 from another conductor strip 54 which islonger than conductor strip 46 and extends to close by the inner end ofbushing 36. This conductor strip 54 is bent at 54a as shown to bring itsend 54b between theend 46b of the strip 46 and the edge of the hole 36aof the bushing 36. This conductor strip 54 also has welded to it a plate540 which can bear against the contact point 50a on the conductor strip50. Adjacent this conductor strip 54 is another insulation strip 56 ofthe same size as strips 44, 48 and 52. Adjacent this insulation strip 56is a small plate 58 against which bear the heads of two bolts 60, thesebolts passing through appropriate holes in this plate and all of theabove mentioned strips, having suitable insulation tubes 62 around theirstems and being threaded to screw into tapped holes 380 in the side 38bof the frame 38 to hold all these strips tightly together and to thisframe.

A small pin 63 of insulation material is fastened to the conductor strip42 and extends through a suitable hole 46c in the conductor strip 46.This pin serves to support the conductor strip 50 which might otherwisebe bent permanently by the force of the plate 54c bearing against thecontact'point 50a as will be understood.

The cable 12 which enters the jack at hole 24a contains two wires 12aand 12b. Wire 12a is electrically connected to the end 46d of theconductor strip 46 which end extends beyond the insulation strips 44 and48 on 'the sides thereof, and wire 12b is electrically connected to theend 54d of the conductor strip 54. The conductor strips 42 and 50 areelectrically connected together by a short piece of wire 64. A twine 66tied to the cable 12 and to the rod 32 prevents the cable from beingpulled out of the jack and thus insures that no strain will be put onthe electrical connections.

Referring now to Fig. 3 this shows the plug B (or B) inserted in theabove described jack. This plug comprises a metal jacket 68 filled witha plastic insulating material 70in which'there are embedded in separatedrelation two conductors 72 and 74. Conductor 72 is located at the centerof the plug and extends out to the end thereof where it emerges from theplastic and forms a necked nipple 72a. From the neck of this nipple thesurface tapers outward to form a cam-surface 72b (see Fig. 2a) beyondwhich and separated therefrom by an extended portion 78a of the plastic70 is a metal ring 73 embedded in the said plastic 70. This ringprovides a hard bearing surface for the end of the plug as it slides inthe bushing 36 to save wear of the plastic 70a. Behind the ring 73 is asleeve portion 74a formed at the end of the conductor 74 which is inturn insulated from the bearing ring 73 and from the conductor 72. Thesleeve 74a is separated from the plug jacket 68 by another portion 7012of the plastic 70. The outer end of the plug which is inserted in thejack is smaller in diameter than the end which the cable 18 enters, andthis reduction in diameter results in a shoulder 68a on the jacket 68.This shoulder bears against the rim of the hole 36a in the bushing 36when the plug has been fully inserted. A cover 76 of insulation materialfits around the metal jacket 68, as shown, and is held in place by a setscrew 6812. A spring 79, having a large diameter portion 79a which fitssnugly around the end of casing 76 and having a small diameter portion79!; which fits snugly around cable 18, prevents cable 18 from beingsharply bent where it'enters the plug.

As the plug enters the jack the rounded nipple 72a first strikes the end54b of the conductor strip 54 to the other end 54d of which the wire 12bof cable 12 is connected. This end 5411 being bent as shown furthermovement of the plug pushes it in a direction away from the axis of thejack, and as a consequence the plate 54c on the conductor strip 54 isseparated from the contact point 50a on the conductor strip 50. As theplug continues into the jack this end 54b rides along the plugscam-surface 72b, past the plastic 70a and the ring 73 and comes to reston the sleeve 74a when the plug is fully inserted. Meanwhile as the plugis moving in to this fully inserted position the nipple 72a strikes theend 46b of the conductor strip 46 to the other end 46d of which theconductor 12a is connected. This end 46b having an indent therein asshown, further movement of the nipple pushes it away from the axis ofthe jack, and as a consequence the plate 46a on the conductor strip 46is separated from the contact point'42a on the conductor strip 42. Whenthe plug is in its fully inserted position the end 4612 of the conductorstrip 46 rests in the neck of the nipple and this engagement serves toprevent the weight of the jack from separating it from the plug.

The cable 18 is comprised of two wires 18a and 18b identical to thewires 12a and 12b of the cable 12. Wire 18a is electrically connected tothe conductor 72. Thus when the plug is fully inserted in the jackcurrent in wire 12a flows through the conductor strip 46 to the nipple72a from whence it flows along the conductor 72 and into the wire 18a ofthe cable 18. Likewise current in the wire 18b flows along the conductor74 to the sleeve 74a from which it passes to the conductor strip 54 andleaves the jack through wire 12b. The direction of the flow may, ofcourse, be opposite to'this, and if alternating current is used thedirection changes with each cycle.

If theplug is'removed from the jack the current flowing in wires 12::and 12b is short circuited. Current can then only How from wire 12a toconductor strip 46 and into conductor strip 42 because the removal ofthe plug allows the plate 46a on conductor strip-46 to-movc againstcontact point 42a on conductor strip 42. Also removal of the plug allowsthe plate 540 on conductor strip 54 to come in contact with point'50a onconductor strip50,'and conductor strip 42 'is connected to conductorstrip 50 by wire 64. The other parts of the circuit shown in Figs. 6,7'and 8 are arranged to be responsive to such and the plugs B and B areshown diagrammatically, the plugs are shown inserted in their respectivejacks so that conductor 12a entering jack A is elfectively connectedacross the closure by conductor 18a to a corresponding conductor 12aleading from jack A, and conductor 12b likewise entering jack A iseffectively connected across the closure by conductor 18b to acorresponding conductor .12b leading from jack A. In practice conductors12a and 12b may enter another jack associated with another protectedclosure and so on for a number of such closures in series on thecircuit, but after the last such closure the conductors are joinedthrough a variable resistor 78 as conductors 12a and 12'b are shown tobe joined in the drawings. Conductor 12b is grounded at ground point 80,and conductor 12a is connected through a galvanometer 82 to one side ofa battery or other source of energy 84 the other side of which isgrounded at a ground point 86. When the closure is closed and the plugsB and B are fully inserted in their respective jacks A and A battery 84drives a current through the circuit comprising galvanometer 82,conductor 12a, conductor 18a, conductor 12a, variable resistor 78,conductor 12b, conductor 18b, and conductor 12b. The variable resistor78 is then adjusted until this current is just suilicient to keep thegrounded galvanometer pointer 82a half way between two galvanometercontact points 8222 and 820. Both these galvanometer contact points areconnected through the windings of a relay 88 to one side 90:: of asecond battery 90 the other side 90b of which is grounded. Relay 88 isarranged so that when it is energized its armature 88a releases andpermits the closing of a switch 92 which completes an alarm circuitcomprising the battery 90, switch 92, signal light 94 and bell 96.

Turning to Fig. 7, if the closure is opened and the plugs pulled out ofthe jacks conductor 12a is effectively connected to conductor 12b injack A and current continues to flow through galvanometer 82, butbecause the resistance provided by those parts of the circuit beyondjack A have been removed this current is increased to the extent thatthe galvanometer pointer 82a moves until it touches galvanometer contactpoint 82c. This energizes relay 88 which in turn closes switch 92 and asignal is produced.

Likewise, considering Fig. 8, if there is an accidental break in thecircuit supplied by battery 84, as at 94, or if an unauthorized intruderis able to cut the circuit in an effort to enter the premises or renderthe system inoperative, (for instance by cutting through the closure)this stops all current in galvanometer 82, whereupon galvanometerpointer 82a falls back against galvanometer contact point 82b. This alsoenergizes relay 88 which in turn closes switch 92 and again visible andaudible signals are produced.

Finally, if in an effort to enter the premises without disturbing thecircuit, an intruder only partly dislodges a plug from one of the jacksan alarm will nevertheless be given. Thus in Fig. 9 the nipple 72a,illustrated diagrammatically, is shown to be in contact with the end 54bof conductor strip 54 after the plub B has been partly removed from itsjack A, but it is clear that the circuit across the closure is brokendespite this contact. Consequently current stops flowing in thegalvanometer 82 and an alarm results as previously described.

One advantage of my improved invention lies in the fact that the jacksand plugs are easily installed on any movable closure. It is onlynecessary to have fixed frames which most closures have, to which thejacks may be secured. The cable 18 may be fastened to any closure.

Another advantage of my invention is that the jacks and plugs are smalland hang out of the way so as not to interfere with the normal use ofthe door. At the same time, however, the jacks and plugs are ruggedenough and the cable sturdy enough to withstand rough treatment withoutinjury.

And still another advantage of my invention is that this portion of thealarm circuit is disposed where it can be easily set when the buildingis closed, and can be readily seen by one desiring to inspect it. Forthis reason it is also easily repaired. It cannot, however, be tampredwith by one outside the building for when the jacks and plugs areproperly installed the door cannot be opened far enough to enable anyone outside the building to reach in and render them inoperative withoutfirst producing a signal.

I claim:

1. The combination with a sliding closure movable relative to a frame ofan electrical burglar alarm circuit comprising electrical alarm signalmeans and a pair of elements adjacent each sliding edge of said closure,one element of each pair of elements being a jack and the other elementbeing a plug, conductors connecting said signal means with the jack ofone of said pairs of elements, the jack connected with said signal meansbeing flexibly anchored to said frame, the plug of said one pair ofelements being flexibly secured for movement with the closure,conductors extending across said closure and interconnecting said pairsof elements, the jack and plug of the other pair being flexibly linkedwith the closure and frame, a resistor, conductors connecting saidresistor with said other pair of elements, the jack and plug of eachpair being electrically separably connected so that upon predeterminedmovement of said closure the force of such movement effects separationof at least one pair of said elements so as to cause said signal meansto give an alarm.

2. The combination with a movable closure having a frame at leastpartially surrounding the closure of a first conductor meansstationarily attached to the frame and having at one end thereofelectrical connecting means, a second conductor means fastened onto theclosure for movement therewith and having a connecting means at one endthereof electrically separably connected with the first mentionedconnecting means in such manner that movement of the closure separatesthe connector means and breaks the circuit, a signalling circuitincluding said first and second conductor means and connecting meanswhereby a signal is actuated upon movement of said closure.

3. The combination according to claim 2 wherein one of said connectingmeans is a plug and the other is a jack.

4. The combination according to claim 2 wherein the connecting means ofsaid first conductor means is anchored to the frame by a chain wherebyupon movement of the closure the chain is put in tension taking thestrain off of the first conductor means.

5. The combination according to claim 3 wherein said first conductormeans has a pair of conductor wires and said jack has a pair of springcontacts respectively connected to the terminals of said conductorwires, said plug having a pair of fixed insulated contact meansrespectively engaging said spring contact means when the jack and plugare coupled so as to complete the circuit through said first and secondconductor means, said jack and said plug.

6. The combination according to claim 3 wherein said first conductormeans has a pair of conductor wires and said jack has a pair of springcontacts respectively connected to the terminals of said conductorwires, said plug having a pair of fixed insulated contact meansrespectively engaging said spring contact means when the jack and plugare coupled so as to complete the circuit through said first and secondconductor means, said jack and said plug, said jack having a pair offixed contacts electrically connected together and so arranged as to berespectively contacted by said spring contacts when the jack and plugare separated so as to short the circuit from one of the wires of saidfirst conductor means to the other of said wires upon such separation ofthe jack and plug.

7. The combination with a movable closure having a frame at leastpartially 'sourrounding the closure of a first conductor meansstationarily attached to the frame and having atone end thereofelectrical connecting means, a second conductor means fastened onto theclosure for movement :therewith and having a connecting means at one endthereof electrically separably connected with the first mentionedconnecting means in such manner that movement of the closure separatesthe connector means and breaks the circuit, a signalling circuitincluding said tfirst and second conductor means and connecting meanswhereby :a signal is actuated upon movement of said clo- .sure,.saidfirst and second conductormeans each including a pair of Wires and saidsignalling .circuit 'being connected across said Wires of said firstconductor means, a resistor connected across the wires of said secondconductor means soas to complete and balance the circuit to thesignalling m ans whereby no si l i g en whil the closure remains closed.

References Cited in the file of this patent UNITED STATES PATENTS

